This invention relates to a container coupling tool for coupling containers laid one on another.
Shipping containers are laid in many tiers on a ship and transported. If they were simply laid one on another, they might collapse when the ship rolls and pitches on the water. Thus, each container is coupled to the containers immediately above and below by container coupling tools.
One known container coupling tool comprises a tool body having top and bottom protrusions which can snugly fit in holes formed in container corner fittings. The tool body is formed with a bore extending from the top face of the top protrusion to the bottom face of the bottom protrusion. A rotary shaft is rotatably inserted in the bore. A top cone and a bottom cone are secured to the top and bottom of the rotary shaft over and under the top and bottom protrusions. By pivoting the handle, the top and bottom cones are turned together with the rotary shaft between two positions where they engage and disengage from the upper and lower containers, respectively.
To couple two containers together with such a container coupling tool, the handle of each coupling tool is pivoted to turn the rotary shaft to the position where the entire top cone is inside the perimeter of the top protrusion. In this state, the top cone of each coupling tool is inserted into the hole of the respective bottom corner fitting of a container hung in the air by e.g. a lifting spreader. Then, with the top cone received in the corner fitting, the handle is pivoted to turn the rotary shaft to the position where the top cone engages in the corner fitting hole and the entire bottom cone is inside the perimeter of the bottom protrusion. The coupling tools are thus coupled to the container.
The container is then placed on another container by inserting the bottom protrusion into the respective top corner fitting holes of the lower container, and the handle is pivoted to turn the rotary shaft to the position where both ends of the bottom cone engage in the respective corner fitting hole.
When a container is hung in the air with the coupling tools of this type coupled to its bottom, if the handle of any coupling tool is turned inadvertently by e.g. colliding against an object, its top cone may disengage and the coupling tool may drop from the container.
In order to solve this problem, the container coupling tool disclosed in examined Japanese utility model publication 5-23514 has a locking means for preventing the top cone from turning to its unlocked position to prevent the dropout of the coupling tool.
In order to prevent undue turning of the top cone when the coupling tool is used either upside up or down, the locking means are made up of a large number of parts. Assembling such a coupling tool is very troublesome and its manufacture is costly.
An object of this invention is to provide a container coupling tool which can reliably keep the topside cone engaged and which is small in number of parts and thus easy to assemble.